It is known that in order to fly at low speed in complete safety, for example during take-off and landing, some aircraft, in particular commercial civil airplanes, have high-lift systems for altering their wing unit intended for cruising at high speed. The aim of these high-lift systems is to momentarily increase the surface area and camber of the wing profile of aircraft, also ensuring greater lift.
The high-lift systems used are basically leading edge slats, arranged in the front portion of a wing, and trailing edge flaps, fitted in the rear portion of said wing. These slats and flaps are movable under the action of an actuating mechanism allowing them to assume either a position in which they are stowed into the wing, or at least one extended position, which is set back and inclined relative to said wing.
As a general rule, the rotation that a leading edge slat undergoes between its stowed position and its extended position is very slight, meaning that the corresponding actuating mechanism can be simple and is easily fully stowable inside the wing in the stowed position.
By contrast, the rotation and the backwards movement that a trailing edge flap has to undergo between its stowed position and its extended position are considerable, resulting in a complex, heavy and voluminous actuating mechanism. These drawbacks are exacerbated by the fact that the actuating mechanisms of all the trailing edge flaps of a wing are generally driven, in a centralised manner, from a single drive shaft. In addition, in these known high-lift systems, a predetermined rotation of the trailing edge flap corresponds to an extended position.
On account of their large volume, these actuating mechanisms of the trailing edge flaps cannot be housed inside the wings and are arranged for the most part outside said wings, projecting from the lower surface of said wings, as shown in U.S. Pat. No. 4,471,928 for example. To limit the aerodynamic disturbances caused by these external actuating mechanisms, each mechanism is contained in a profiled fairing suspended below the lower surface of the corresponding wing. Despite this precautionary measure, the drag resulting from the presence of these profiled fairings remains significant, and this may impair aircraft performance. Furthermore, since the rotation of the trailing edge flap is linked to its extension, optimum aerodynamic effect of this flap is impossible.
It will be noted that U.S. Pat. No. 3,655,149 and EP 0 411 680 disclose trailing edge flap systems, housed in part in the wing bearing said flap and in part in said flap. However, in these known systems, the inclination of a trailing edge flap is controlled by the extension movement of said flap.
In addition, other objects, desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background.